Automatic egg candler



May 17, 1955 e. N. BLISS AUTOMATIC EGG CANDLER Filed May 26. 1953 WAR TNQQ POWER SOURCE AMPL/F/ER Q 1' I M INVENTOR.

GEORGE N. BLISS BY United States Patent AUTOMATIC EGG CANDLER George N.Bliss, Ithaca, N. Y. Application May 26, 1953, Serial No. 357,400

2 Claims. (Cl. 209-111) This invention relates to automatic egg candlingmachines, and particularly to the detection and elimination ofunmarketable eggs known to the trade as bloods. While such eggs are notdangerous to health, they are not acceptable to customers and manyStates have laws forbidding their sale for human consumption. Eggs todayare inspected by the candling method by which the inspector holds theegg in front of a candling lamp which sends a beam of ordinary lightthru the egg, illuminating the contents which is more or lesstranslucent. The inspector turns the egg around in various positions inthe beam and Works in a darkened room. Blood clots show up as dark orreddish spots, or if there is much blood the whole egg may appear red.However, smaller blood spots are often missed, while many good eggs withheavy shells or dark colored yolks are mistakenly rejected as bloods.

It is difi'icult to find a sufficient number of qualified persons tocandle all the eggs, since the work involves manual dexterity,considerable judgement and skill, and

requires work in the dark against lights, which is hard on the eyes.Enormous numbers of eggs must be handled each year; and since the lawrequires that most of them be candled, that process constitutes abottleneck that adds considerably to the cost to the consumer. Whileelaborate machines have been developed to facilitate the movement ofeggs thru packing plants, the eliminating of the bloods is still done bythe human eye..

Various attempts have been made to solve this problem in the past bytransmitting various types of light thru the egg to operate photocellsor other light responsive devices to control electric circuits actuatingsorting mechanisms. While many combinations of particular lights andfilters have been tried, they have heretofore failed to produce asatisfactory solution capable of commercial application. 1

The present invention uses a mercury lamp as the source of light,filters out its green line at about 546 m along with other blue andviolet lines beyond that point, and uses solely the wave lengths at 577m, and 579 m which, being closely adjacent, form a narrow band in theyellow light range. This 577-579 m band, while very much narrower thanany filter could produce, nevertheless has a finite width and area which'sufficiently coincides with a hemoglobin absorption band so as to becapable of variation according to the presence of blood,

and in sufiic'ient extent to operatively modify the over-- all'qu'antity 'of light falling on the light sensitive cell. It appears toovercome the difiiculties associated with thewave-lengths and filterspreviously used, and to make possible the practical elimination ofbloods by automatic mechanical means.

Referring now to the drawings forming part of this specification,

Fig. 1 is a diagram of the relative intensity or transmission oflight ofvarious wave lengths thru a normal egg, and thru a blood egg, togetherwith the location of lhezprincipal lines of mercury light. It also showsthe efiect of the filter here used in eliminating the light at. 546 mand transmitting the light at 577-579 111,41. to 0perate the device.

Fig. 2 is a diagrammatic view of the mechanism, partly in section,showing the mercury light, the filter, egg, conveyor belt, lightresponsive cell, amplifier and relay, and a kick-out mechanism forremoving the egg when blood is indicated.

Referring first to Fig. 1, the wave lengths of light are indicated from500 m which is the green blue range, to 700 m which is the red-orangerange. One ma'iS' a millimicron, that is, equal to .000001 millimeter,the m being a unit that is commonly used in measuring the wave,

length of light. The light transmissibility of an egg extends to bothhigher and lower values than shown in the diagram, but since only a verynarrow part of that range is used in the present invention there extendthe diagram further.

The curve marked 1 illustrates the relative light transmission atvarious wave lengths for a normal egg, show,- ing that the maximumtransmissibility to light is between 600 m and 700 m that is, in thered-orange range. This area has been used in some prior devices, becauseit was known to be an area of maximum transmissibility, but is not usedin the present invention.

Curve 2 illustrates the relative light transmission at various wavelengths for a typical blood egg, and it will be noted that the curve hasa slight dip (a) at about 546 m,u and a more pronounced dip (b) at about575-580 m These dips are due to absorption of green light at about540-550 m r and to absorption to a greater extent is no need here to ofyellow light at about 575-580 m when attempting to:

pass thru hemoglobin.

Curve 3 illustrates the transmissibility of the filter used in thisinvention to practically eliminate the light in the 540-550 m (green)region but 575-580 m region and beyond.

The green line of the mercury spectrum at 546mg.

is indicated by thereference numeral 4, and the yellow lines from themercury light at 577 and579 m are il'l-n dicated by the referencenumeral It is difiicult to make a filter which will sharply limit.

the precise wave lengths of light to a sufficiently narrow color bandfor this problem. While it is possible'to use a filter to produce theoperative light, it is preferable under the present invention to make,use of mercury light and use a filter only to black out one of themercury" lines at 546 m (a green line) while not interfering with the577 and 579 m (yellow) lines of the mercury light, which being closetogether and favorably placed in relation to the major dip (b) of theblood egg curve 2 makepossible an interaction capable of solving theproblem.

This action is as follows.

Considering only the 577-579 m lines of the yellow light-which is heretheonly region permitted to operate-this region, while very sharp andnarrow, has never- -theless a finite width so that some quantity oflight is passed, this quantity varyingdirectly with the height of thegeneral egg transmission curve in that region. If the egg is normal,without blood spots or hemoglobin, the amount oflight passed is directlyproportional to the height of the 577-579 m hand up to the point whereit meets the curve 1. On the'other hand, if blood is present, the amountof light transmitted is proportional to where that light band meets thecurve 2, a considerably lesser amount. While this difference in amountwill vary with great, the fact that in the present invention it isconcentrated on a narrow precise band, instead of a broader area such asprevious inventions have defined by filters, prevents the smallvariations from being lost orobscured in the larger mass,

- so that the full effect of relatively small variations can PatentedMay 17, 1955 pass the light in the h ut lizd suc essfully t .cncta the ih sens t ve r jector mechanism.

This mechanism is illustrated in Fig. 2 and consists of a mercury .lightconnected with a suitable electric power source 11, \the lamp 1!) beingpreferably enclosed in a box 12 having a window 13 thru which the beamof mercury light may shine on the egg E. To eliminate the 546 m lightand pass 577-579 m light a suitable filter 14 may be placed in thewindow 13. Such filters are available commercially, as for exampleCorning #3480 or Wratten E2#22. When a high pressure mercury arc is usedas the light source in conjunction with a red sensitive cell at thereceiving end, an additional red absorbing filter such as Corning #4784may be required.

The filter may be located anywhere in the beam of light between thelight source 10 and the receiving cell 16, since it is immaterialwhether the 546 m light is filtered out before or after it passes thruthe egg E, so long as it is eliminated before it can reach theresponsive cell 16 so as not to actuate it. For example, the filtermight be placed between the egg E and the receiving cell 16. However, itis generally more convenient to locate the filters at 14 in the window13 as shown instead of under the conveyor belt 20.

The conveyor belt 20 is conventionally shown in crosssection -in Fig. 2and may have various forms, as such belts are commonly used in thehandling of eggs in packing and processing plants. It is only necessarythat it have an opening 21 or other path to allow the beam of light topass thru the egg and fall upon the receiving cell 16. Since the actionof the light and electricity is practically instantaneous the belt 20can be run continuously, without stopping for each egg, and consequentlythe machine can work very rapidly, as compared with hand candling.

The receiving cell 16 is preferably enclosed in a box 23 which is opaqueexcept where the beam of light enters it, and the cell 16 may be of anyof the well known types which vary an electric current in response tothe impact of light. available; some generate an electric voltage withinthemselves when light falls upon them, others use an external currentsupply but vary their resistance according to the light that falls uponthem so as to vary the current accordingly. Examples of light sensitiveelements include selenium cells, copper oxide cells, photoemiss ivetubes, and 'photoconductive tubes such as the lead sulphide tubes. Newphotosensitive materials are being continu ally. discovered such asgermanium crystals and the like. Cells such as selenium and copper oxidecells generate a current when acted upon by light, while most otherdevices in use pass a curent generated by an auxiliary source. In anyevent, a variable voltage or current is produced which changes accordingto the amount of 577-579 m light which strikes the cell 16 andaccordingly registers the presence or absence of hemoglobin in the egg.

This current or voltage is transmitted to the amplifier; 25 where it isamplified to whatever extent desired. For visual operation andcalibration a dial indicator 26 is connected to the amplifier 25, andfor mechanical operation the amplifier 25 operates a relay 30. Thisrelay 30 is of the hold open type, consisting for example of anelectro-magnetic coil having a solenoid plunger 31 operating a contactswitch 32 in the circuit of the battery 33 which in turn can energize anelcctro-magnet 34.

So long as enough light falls on the receiving cell 16 to maintainsuflicient current thru the amplifier to hold the relay 30 open, thecircuit of the electro-magnet 34 is broken at the switch. points 3.2 andthere is no tendency to reject the eggs moving along'the belt 20. But ifthe amount of transmitted 577-579 mg light is appreciably diminished bythe. hemoglobin of a blood egg, the current in the amplifier circuitmaybe reduced sufficiently so that the plunger 31 is no longer heldVarious types are commercially in by the relay and wi .fa l. c osing theci cuit of in ad the electro-magnet 34, which attracts the movable arm40 and forces the egg E ofi the belt. In other words, the rejectingmechanism only operates when a blood egg is present. If the egg is good,or there is no egg present, sufficient light from the lamp 10 falls onthe receiv' ing cell 16 to continuously maintain sufficient amplifiedcurrent to hold the relay switch 32 open.

It will be understood that the rejecting mechanism 1, need notnecessarily operate directly under the light,

but its action may occur anywhere later along the conveyor thru the useof so-called memory devices which are now frequently used in automaticsorting machines. Whether the rejection is immediate or postponed isimmaterial to the present invention, which is particularly concernedwith obtaining a primary initiating device capable of instantlydistinguishing blood eggs from normal eggs within the range required incommercial practice, so as to equal or excel the precision of the humaneye as now used in ordinary candling.

While I have in the foregoing described certain specific forms by way ofexample, it will be under-stood that they are merely for purposes ofillustration to make clear the principles of the invention, which is notlimited to the particular forms shown but is susceptible to variousmodifications and adaptations in different installations as will beapparent to those skilled in the art without departing from the scope ofthe invention as stated in the following claims.

I claim:

1. In an automatic egg candler, the combination of a light source havinga strong narrow yellow band at about the region 577-579 mg, a lightsensitive receiving cell responsive to light in said region, a lightfilter located between the light source and the light sensitivereceiving cell, the filter being adapted to pass light waves in said577-579 mu region and block the transmission of light waves of othercolors, an egg conveyor for carrying eggs in rapid succession thru thebeam of light between said light source and the light sensitivereceiving cell so that light of said wave lengths 577-579 mg will passthru each egg to the receiving cell, an electric amplifier connected tosaid receiving cell, a relay connected to and operated by saidamplifier, a switch connected to and operated by said relay, a rejectingcircuit connected to and operated by said switch when the current in theamplifier and relay circuit falls below that determined by the beam ofsaid light thru a normal egg to that determined by absorption of lightin said region by hemoglobin in an egg, and a rejector mochanismconnected to and operated by said rejecting circuit to shift a blood eggto a different path from that of the normal eggs on said conveyor.

2. In an automatic egg candler, the combination of a mercury lightsource having a strong narrow yellow band at about the region 577-579mm, a light sensitive receiving cell responsive to light in said region,a light filter located between the light source and the light sensitivereceiving cell, the filter being adapted to pass light Waves in said577-579 my region and block the transmission of light Waves of othercolors, an egg conveyor for carrying eggs in rapid succession thru thebeam of light between said light source and the light sensitivereceiving cell so that light of; said wave lengths 577-579 m will passthru each egg to the receiving cell, an electric amplifier connected tosaid receiving cell, a relay connected to, and operated bysaidzunplifier, a switch connected to and operated by said relay, arejecting circuit connected to and operated by said-switch when thecurrent in the amplifier and relay circuit falls below that determinedby a beam of said light thru a normal egg to that determined byabsorption of light in said region by hemoglobin in an egg, and arejector mechanism connected to and operated 'bysaid-rejecting circuitto shift a blood egg to a different path from that 2,244,826 of thenormal eggs on said conveyor. 2,321,900 2,481,567 References Cited inthe file of this patent UNITED STATES PATENTS 5 1,946,980 Loomis Feb.13, 1934 2,118,794 King May 24, 1938 2,186,196 Haugh Jan. 9, 1940 6 CoxJune 10, 1941 Dooley June 15, 1943 Brown Sept. 13, 1949 OTHER REFERENCESColor Grading by Electronics, by Derosier, Billerbeck and Smith, FoodEngineering, September 1953,

